The present invention relates to chain driven bicycles. More particularly, the present invention relates to a sprocket used on such bicycles which has stiffening fins to axially reinforce and strengthen the sprocket.
The majority of bicycles are chain driven in that the rider pushes downwardly with his or her feet on pedals placed at the ends of crank arms which are attached to a chain sprocket. The pedaling force rotates the typically circular or semi-circular sprocket. A chain interconnected between the teeth of the sprocket and a gear associated with the rear wheel of the bicycle is moved by the rotation of the sprocket, causing the rear wheel to rotate and propelling the bicycle forward.
In order to conserve the amount of materials used and to minimize the weight of the sprocket, it is typically constructed so as to be relatively thin. So long as only a moderate force is applied to the pedals, the sprockets in use today function adequately. However, when large forces are applied to the pedals, the sprocket tends to flex axially. This is oftentimes the case with bicycle moto-cross (BMX) or mountain bikes which are generally ridden off-road or under other strenuous conditions, such as dirt jumping and ramp riding. When applying great force to the pedals axial flexing or even permanent bending of the sprocket may occur. For example, if the rider is jumping or performing tricks or if the rider lands or crashes in such a way, sprocket bending may occur. This flexing or bending can cause chain disengagement from the sprocket and/or difficulty in shifting gears. Chain disengagement can result in valuable time lost in racing situations, and is also quite dangerous to the rider as control of the bicycle may be lost and the loose chain can become tangled with objects on and around the bicycle. In extreme cases, the rider is not able to continue to ride at all.
Therefore, what is needed is a chain sprocket which is reinforced and strengthened axially in order to prevent axial flexing. Further, there is a need for a reinforced chain sprocket which can be used in a variety of existing bicycles without modifying other components of the bicycle. The present invention fulfills these needs and provides other related advantages.